1. Technical Field
This disclosure generally relates to data processing, and more specifically relates to the moving of a logical partition.
2. Background Art
Since the dawn of the computer age, computer systems have evolved into extremely sophisticated devices that may be found in many different settings. Computer systems typically include a combination of hardware (e.g., semiconductors, circuit boards, etc.) and software (e.g., computer programs). As advances in semiconductor processing and computer architecture push the performance of the computer hardware higher, more sophisticated computer software has evolved to take advantage of the higher performance of the hardware, resulting in computer systems today that are much more powerful than just a few years ago.
The combination of hardware and software on a particular computer system defines a computing environment. Different hardware platforms and different operating systems thus provide different computing environments. In recent years, engineers have recognized that it is possible to provide different computing environments on the same physical computer system by logically partitioning the computer system resources to different computing environments. The Series p computer system developed by IBM is an example of a computer system that supports logical partitioning. If logical partitioning on a Series p computer system is desired, partition manager code (referred to as a “hypervisor” in Series p terminology) is installed that allows defining different computing environments on the same platform. Once the partition manager is installed, logical partitions may be created that define different computing environments. The partition manager manages the logical partitions to assure that they can share needed resources in the computer system while maintaining the separate computing environments defined by the logical partitions.
A computer system that includes multiple logical partitions typically shares resources between the logical partitions. For example, a computer system with a single CPU could have two logical partitions defined, with 50% of the CPU allocated to each logical partition, with 33% of the memory allocated to the first logical partition and 67% of the memory allocated to the second logical partition, and with two different I/O slots allocated to the two logical partitions, one per partition. Once logical partitions are defined and shared resources are allocated to the logical partitions, each logical partition acts as a separate computer system. Thus, in the example above that has a single computer system with two logical partitions, the two logical partitions will appear for all practical purposes to be two separate and distinct computer systems.
There are times when a logical partition needs to be moved. For example, if a new computer system is installed to take over the functions of an old computer system that is running logical partitions, the logical partitions on the old computer system need to be moved, or migrated, to the new computer system. However, the operation of migrating a logical partition is time-consuming. If the logical partition cannot be used until the migration is complete, unacceptable delays result. Without a way to migrate a logical partition in a way that allows using the logical partition before the migration is complete, the computer industry will continue to suffer from excessive downtime when migrating logical partitions.